No abstract

The reactions of e, ;, H. and O H with phenol have been studied. The corresponding rate constants were 1.8 x 107, 1.8 x 109 and 1.4 x 1010 M-1 sec-1, respectively. The product detected after eal, and H. attack was the H adduct (~3 3 0 0~ = 3800 M-1 cm-1). The initial product of OH. attack was the OH adduct (E3300A = 4400 M-1 cm-1). Both H and OH adducts are probably mixtures of isomers. OH adducts subsequently undergo either unimolecular elimination of water to form the more resonance-stabilized phenoxyl radical, 40. (E~OOOA = 2200 M-1 cm-I), or bimolecular radicalradical reactions. The elimination is catalyzed by H+, OH-and HPOa-ions. There are indications of different rates of catalysis for different isomers of the OH adduct. The uncatalyzed rate of elimination is < 103 sec-1. The elimination was also detected from OH adducts of p-cresol (to give P-CH~C~H~O., E4050A = 2400 M-1 cm-1) and tyrosine. The ability to eliminate water appears to be a general property of OH adducts of phenols.

No abstract

The absorption spectra of the radicals HC6H5No2 and OHC6H5N02 in aqueous solutions have been obtained. These transients have a strong absorption at 4100A and their molar extinction coefficients are both 3700 M-l cm-'. The following rate constants have been measured :x 106 M-' sec-' ; k(OHC6HSNO2 +OHC6HsNo2) = (6.0% 0.4) x lo8 M-l sec-'. About 25 % of the reactions between two nitro-hydroxycyclohexadienylradicals lead to nitrophenol-isomers by disproportionation. The majority of these reactions lead to other products (probably dimers by combination) which exist in acid and basic forms, the latter having strong absorptions in the visible range. These products are believed to be derivatives of nitro-cyclohexadiene.